We have developed a new method for monitoring the releasing patterns of the hypothalamic hormones in conscious monkeys. Female castrated monkeys (Macaca fuscata) were used after implamtation of a silasdc capsule containing estradiol. Under anesthesia, the orbital contents were removed. A double lumen needle was inserted along the medial wall of the superior orbital fissure into the upper part of the pituitary adjacent to the stalk. Heparinized saline was constantly fed into the infusion tube at a rate of 1.6ml / 15min. Every 15-min faction for a consecutive 12-h or longer period was analyzed for hypothalamic hormones by a RIA. Blood samples obtained before and during the experiment also were analyzed for GH and cortisol by a RIA.Growth hormone - releasing hormone (GHRH) often increased from base levels to a peak. GHRH pulses in all animals were 60 in 84h. Themean (<plus-minus>SEM) GHRHpulseintervalwas79.5<plus-minus>6.3min. ThemeanpeakievelofGHRHpulseswas<plus-minus>2. lpg/15min, rangi
… Moreng from7. OtolO5pg/15min. The intervals between major GHRH pulses (peak value>15pg/15min ; increment>lopg/ 15min) were 148.0<plus-minus>16.4min, ranging from 30 to 300min. Seventy - six percent of GH pulses were found to synchronize with the GHRH pulses. Plasma cortisol was remarkably increased during the perfusate collections, suggesting surgical stress. Our findings suggest that the changes of the hypothalamic hormone in the perfusate collected by our procedure represent its secretary patterns from the hypotIn other groups of animals the similar experiments have been performed to elucidate the releasing patterns of corticotropin-releasing hormone (CRID and gonadotropin - releasing hormone (ONRH) in monleys under the same experimental conditions. Female castrated monkeys, were used after sc implantation of a silastic capsule containing estradiol.Although several methods have been developed for assessing the releasing pattems of hypothalamic hormones, such as portal blood collection (Carmel et al., 1976 ; Neill et al., 1977), the push - pull perfusion of the hypothalamus (Levine et al., 1982), some technical and theoretical problems restrict their wide use. Our technique, developed as an alternative method, permits the hypothalamic hormonal release in unanesthesized animals. Less